Package g1901_2000.s1997_first_day_where_you_have_been_in_all_the_rooms

Class Solution

java.lang.Object
g1901_2000.s1997_first_day_where_you_have_been_in_all_the_rooms.Solution
public class Solution extends Object
1997 - First Day Where You Have Been in All the Rooms.

Medium

There are n rooms you need to visit, labeled from 0 to n - 1. Each day is labeled, starting from 0. You will go in and visit one room a day.

Initially on day 0, you visit room 0. The order you visit the rooms for the coming days is determined by the following rules and a given 0-indexed array nextVisit of length n:

  • Assuming that on a day, you visit room i,
  • if you have been in room i an odd number of times ( including the current visit), on the next day you will visit a room with a lower or equal room number specified by nextVisit[i] where 0 <= nextVisit[i] <= i;
  • if you have been in room i an even number of times ( including the current visit), on the next day you will visit room (i + 1) mod n.

Return the label of the first day where you have been in all the rooms. It can be shown that such a day exists. Since the answer may be very large, return it modulo 109 + 7.

Example 1:

Input: nextVisit = [0,0]

Output: 2

Explanation:

  • On day 0, you visit room 0. The total times you have been in room 0 is 1, which is odd.

On the next day you will visit room nextVisit[0] = 0

  • On day 1, you visit room 0, The total times you have been in room 0 is 2, which is even.

On the next day you will visit room (0 + 1) mod 2 = 1

  • On day 2, you visit room 1. This is the first day where you have been in all the rooms.

Example 2:

Input: nextVisit = [0,0,2]

Output: 6

Explanation:

Your room visiting order for each day is: [0,0,1,0,0,1,2,…].

Day 6 is the first day where you have been in all the rooms.

Example 3:

Input: nextVisit = [0,1,2,0]

Output: 6

Explanation:

Your room visiting order for each day is: [0,0,1,1,2,2,3,…].

Day 6 is the first day where you have been in all the rooms.

Constraints:

  • n == nextVisit.length
  • 2 <= n <= 105
  • 0 <= nextVisit[i] <= i

  • Constructor Details

    • Solution

      public Solution()

  • Method Details

    • firstDayBeenInAllRooms

      public int firstDayBeenInAllRooms(int[] nextVisit)